Anxiety disorders in youth are: 1) the most prevalent psychiatric disorders, 2) associated with severe disability, and 3) considered gateway disorders-- as they predict adult psychiatric illnesses. Consequently, these disorders are a public health problem that is costly to afflicted individuals, families, and society. Data on whether these illnesses can be prevented is paramount. Systematic efforts to prevent anxiety disorders in youth appear promising in the short term but data on long-term effectiveness and cost-benefits are lacking. This application proposes an evaluation of the long-term impact and cost-benefits of the Coping and Promoting Strength (CAPS) program (6). CAPS is an intervention aimed at preventing the onset of anxiety disorders in offspring of anxious parents, a population at high risk for developing anxiety and related disorders. Data from the PI's NIMH-funded pilot study and large efficacy trial (K23 MH63427 and R01MH077312) demonstrated promising results at a one year follow-up. This proposed study will continue to evaluate these at risk youth (N = 136) over a four year follow-up period as youth transition into the critical developmental stages of adolescence and young adulthood. This study will be the first long-term follow-up of a preventive intervention for anxiety disorders in high risk offspring, making a major contribution t the field. The study also incorporates several innovative features including 1) a cost-benefit analysis of the intervention, 2) the examination of theory-based mechanisms of intervention effects, and 3) biological markers (e.g., cortisol, alpha amylase, and their coordination) that may help predict illness onset and course. The application was prepared in response to PA- 11-260 and addresses several NIH priorities including: 1) developing and evaluating preventive interventions that reduce the incidence of mental illness, 2) assessing mechanisms of intervention effects across many outcomes (e.g., mental disorders/dimensions, functioning) and 3) incorporating findings from translational science by evaluating salivary biomarkers (i.e., those that reflect HPA axis functioning) to help understand psychiatric illness onset and remission. The study uses rigorous scientific methods including multiple informants and independent evaluators. Findings will inform the field about the intervention impact, mechanisms of intervention effects, costs savings, and predictors (including biomarkers) of illness onset and course. Finally, the study also takes advantage of a rare scientific opportunity by collecting data in this sample that duplicate measures in the PIs follow-up study of clinically anxious youth and healthy controls (R01 MH064089; K24 MH096760) creating a database that will enable comparisons of high risk offspring, clinically anxious, and healthy controls on a number of outcomes including salivary biomarkers and a range of dimensional symptoms outlined the NIMH Research Domain Criteria (e.g., executive functioning, emotion control) that will also be available to the scientific community. Thus, the present study makes efficient use of NIH funds.